Multi-stage, multi-zone static bed reforming process and apparatus therefor



3,069,348 ING 7 Sheets-Sheet l Dec. 18, 1962 E. v. BERGSTROMMULTI-STAGE, MULTI-ZONE STATIC BED REFORM PROCESS AND APPARATUSTHEREF'OR Filed July 22, 1959 Dec. 1s, 1962 E. v. BERGsTRoM 3,069,348MULTI-STAGE, MULTI-ZONE sTATc BED REFORMING PROCESS AND APPARATUSTHEREFOR Filed July 22, 1959 7 Sheets-Sheet 2 m7 magg l 165 `o` "ltr iil ii Jij INVENTOR.

69 ERI c; MBERGs-mowlf AGENT E. MULTI-STAGE, MULTI BERGsTRoM 3,069,348ZONE STATIC BED REFORMING Dec. 18, 1962 v.

PROCESS AND APPARATUS THEREFOR Filed July 22, 1959 '7 Sheets-Sheet 3INVLNTOR. Erzlc v. BEmsTFLoM AGEN-r Dec. 18, 1962 E. v. BERGSTROM3,069,348

MULTI-STAGE, MULTLZONE STATIC BED REPORMING PROCESS AND APPARATUSTHEREFOR Filed July 22, 1959 7 Sheets-Sheet 4 INVENTOR. ERI C, V. BERGSTROM AGENT Dec, 18, 1962 E. V. BERGSTROM PROCESS AND APPARATUSTHEREF'OR 7 Sheets-Sheel 5 IGS INVENTOR.

E RIC BERGQTROM AGENT Dec. 18, 1962 E. V. BERGSTROM MULTI 3,069,348 ZONEsTATIc BED REFORMING MULTI-STAGE PROCESS AND APPARATUS THEREFOR 7Sheets-Sheet 6 Filed July 22, 1959 ifa! omN man INVENTOR. PJC. V.BERGSTROM EWE;

AGENT Dec. 18, 1962 E. V. BERGSTROM MULTI-STAGE, MULTI -ZONE STATIC BEDREFORMING PROCESS AND APPARATUS THEREFOR '7 Sheets-Sheet 7 Filed July22, 1959 INVENTOR. E RI C V BE RGSTROMI Nmm AGENT United States PatentChice 3,959,348 Patented Dec. 18, 1962 $69,348 l/IULTli-STAGE,MULZTl-ZGNE STATI() BED RE- FRMING PRCESS AND APPARATUS THEREFR Eric V.Bergstrom, Byram, Conn., assigner 'to Socony Mobil @il Company, lne., acorporation of New York Filed .luly 22, 1959, Ser. No. 828,759 7 Claims.(Cl. 208-64) The present invention relates to reforming and, moreparticularly, to reforming using a platinum-group metal particle-formsolid catalyst and reaction pressures of the order of about 300 poundsper square inch gauge (psig.) or less.

Reforming is the term used to designate the end result of the individualreactions of dehydrogenation of naph- 4thenes, dehydrocyclization, andisomerization of parafiins. Theoretically, dehydrogenation of theparafns to olefins precedes cyclization of the oleiins to formaromatics. Regardless of whether `in actuality the reactions ofdehydrogenation, dehydrocyclization, and isomerization are isolatedreactions or successive reactions or not, the upgrading of naphthapresently is the principal practical use of reforming. Accordingly, whenthe term reforming is used hereinafter it will be used to designate anoperation in which naphtha is upgraded by raising the octane rating(Research or clear) of naphtha. A reforming catalyst is a catalyticmaterial employed in reforming or upgrading naphtha. A platinurn-groupreforming catalyst is a catalyst comprising a carrier or support ofrefractory oxide such as alumina, silica, zirconia, boria and the likefor a metal of the platinum group of metals, ie., platinum, palladium,iridium, etc.

Space velocity or liquid hourly space velocity is the term designatingthe volume of reformer charge stock or naphtha per hour contacting avolume of catalyst, the volume of catalyst being the volume of thereactor which is occupied by the reforming catalyst.

Presently, the preponderant portion of reforming units employing aparticle-form, solid, platinum-group reforming catalyst are unitsoperating under reactor pressures of at least 500 p.s.i.g. Substantiallyall of Athe aforesaid units operate for oir-stream periods in excess ofthree months when the ori-stream period is not interrupted by reason ofmechanical failure or deactivation of the catalyst by reason of causesother than the deposition of a carbonaceous material commonly designatedcoke. In fact, many of the aforementioned reforming units have beenoperating for ori-stream periods of a year or more. The catalystemployed in these units is usually termed a non-regenerable platinumcatalyst and the operation is usually termed a non-regenerating type ofreforming although the catalyst when deactivated only by the depositionof colte can usually be regenerated.

The platinum-group metal reforming catalyst used in these reformingunits operating at pressures of 5 O() p.s.i.g. or more can also be usedfor reforming at pressures below 500 psig. However, at pressures muchbelow, eg., 100 to 20D p.s.i. below, the catalyst must be rcgenerated atintervals of from l2 to 240 hours, while reforming at pressures at 300p.s.i.g. or lower produces better yields of reformate having a givenoctane rating than reforming the same naphtha over the sameplatinummetal group catalyst at pressures of 50G p.s.i.g. or more thenecessary frequent regeneration is an economic disadvantage.

ln order to provide for continuous operation and the frequentregeneration. it has been the practice to employ six reactors, five ofwhich are on-stream while the sixth or swing reactor replaces thereactor being regenerated. This necessitates a considerable amount ofcomplicated piping. Furthermore, only about 83 percent of the totalcatalyst charge to the six reactors is used continuously. In contrast,in the method of the present invention 93 percent of the total catalystcharge is in continuous use. ln addition to the considerable amount ofcomplicated piping required to maintan the swing reactor in the propersequential position, the valving necessary to maintain the swing reactorin the proper place in the reactor train is very complicated. lncontrast with the swing reactor system which requires the switching oflarge valves so that the swing reactor may be used in any position inthe progression through ve reactors, the method of the present inventionrequires no switching of the process streams in and out of each reactorstage, and the large (20-inch diameter) process piping is permanentlyconnected to each reactor stage without the use of valves.

Accordingly, it is an object of the present invention to provide amethod of reforming naphtha at pressures of about 300 p.s.i.g. or lesswherein deactivation of the platinum-metal Group reforming catalyst dueto the deposition of coke requires frequent regeneration of the catalystand the on-strcam period for any single reaction stage is considerablyless than one month, e.g., 12 to 240 hours, employing a plurality ofreaction stages, each reaction stage having a plurality of reactionzones, at least one of said reaction zones being regenerated whilst theother reaction zones in each reaction stage are ori-stream. It isanother object of the present invention to provide a method of reformingnaphtha at pressures of about 300 p.s.i.g. or less employing a pluralityof reaction stages each having a plurality of reaction zones all ofwhich reaction zones in each reaction stage are in fluid communicationwith a charge manifold and an effluent manifold and selectivelyisolating one reaction zone in at least one reaction stage from theaforesaid charge manifold and effluent manifold whilst maintaining fluidcommunication between said charge manifold and said effluent manifoldand the other reaction zones in each reaction stage. lt is a furtherobject of the present invention to provide a presently preferredapparatus for reforming. naphtha in accordance with the present method.Other objects and advantages will become apparent to those skilled inthis art from the following discussion taken in conjunction with thedrawings in which FIGURE l is a ilowsheet showing in a diagrammaticmanner the flow of reactant gases and vapors through a plurality ofreaction stages having a plurality of reaction zones and the flow ofcirculating regenerating gas through the reaction zones o-stream and inthe regeneration portion of the cycle;

FiGURE 2 is a vertical section taken at line Z-2 in FIGURE 3a;

FIGURES 3a and 3b are a vertical longitudinal section of a presentlypreferred reactor having a plurality of reaction stages each having aplurality of reaction zones, all of the reaction zones in each reactionstage being in uid communication with an upper plenum chamber serving asa vapor inlet manifold and all of the reaction zones in each reactionstage being in fluid communication with a lower plenum chamber servingas a vapor outlet manifold;

FIGURE 4 is a vertical section of a rising stern valve mechanismpresently preferred as a closure means between each reaction zone andits plenum chambers;

FGURE 5 is detail sectional view of the valve seat and plug presentlypreferred as a closure means between each reaction zone and its plenumchambers;

FIGURE 6 is a detail cross-section of a removable plug valve seat as analternate closure means between each reaction zone and its plenumchambers; and

FIGURE 7 is a llowsheet illustrating the flow of vapors accesar;

gen and of static beds of particle-form, solid, platinun group metalreforming catalyst. rFha present provides for reforming hydrocarbon in aplurality of action stages with reheating of the vapors between reactionstages. The present method also provides for a plurality of reactionZones in each reaction stage. Characteristic of the method of thepresent invention is the regeneration of the catalyst in at least onereaction zone in at least one reaction stage while hydrocarbon is bereformed in the other reaction zones of each reacton stage.

The present invention also provides a novel reactor for reforminghydrocarbon in a plurality of reaction stages each having a plurality ofreaction zones in which the method of the present invention can bepracticed.

The flowsheet FIGURE 1 is illustrative of one means for reformingnaphtha in the presence of particle-form solid reforming catalyst,preferably a platinum-group catalyst, in a plurality of reaction stagesin which each reaction stage has a plurality of reaction zones. At feastone reaction zone is being regenerated while the other reaction zones ineach reaction stage are ori-stream for reforming the naphtha feed. itwill be observed that the piping, furnaces and gas compressor forheating and circulating the regenerating gas are separate from thepiping, heaters, and gas compressor for heating and circulating thereaction gases.

Illustrative of the method of the present invention is the flow ofvapors and gases through a plurality of reaction stages in which eachreaction stage is divided into a plurality of reaction zones showndiagrammatically in FIGURE 1. Those skilled in the art will understandthat, while only three reaction stages with three reaction zones in eachreaction stage are illustrated, there can be more or less Vreactionstages each having more or less reaction zones. The number of reactionstages will be dependent upon the total amount of catalyst required toprovide the predetermined liquid hourly space velocity (volume of feedper hour per volume of catalyst) and the volume of catalyst contacted bythe feed in producing a temperature drop sucient to require reheating tothe required reaction ltemperature to produce a CS-lreformate ofpredetermined octane rating.

In general, each reaction zone is maintained at a recction pressure notgreater than about 500 p.s.i.g. althot the reaction vessels can bedesigned for reaction pressures of 1000 to 1200 p.s.i.g. Reactiontemperatures of about 800 to about 1000" F. are employed with liquidhourly space velocities (v./hr./v.) of 0.2 to l0. Hydrogen-tonaphtha molratios of about 1/1 to about 1,0/1 are employed.

Naphtha to be reformed in accordance with the present method contains aslittle irreversible catalyst poisons such as arsenic as is practicallypossible. For exampie, the feed naphtha should be essentially free ofarsenic this characterization designates a concentration of arsenicwhich, when the reformer feed is contacted with a. bed of reformingcatalyst containing about 0.35 percent platinum by weight, is insuicientto deactivate said catalyst within the life of the catalyst, for exampletwo years, as determined by other factors such as the temperaturerequired. to produce a reformate having an octane rating of at least 100(R1-|-3 cc.), the yield of reformate, and the mechanical strength of thecatalyst. The feed naphtha should not contain more than 1 ppm. ofnitrogen when employ-- ing a platinum-group metal reforming catalystsuch as a particle-form solid platinum-group metal reforming catalystcomprising about 0.1 to about.l.0, preferably about 0.2 to about 0.4percent by weight platinum and about 0.1 to about 0.8 percent by weightof a halogen on a refractory metal oxide support such as a alumina,silica, or silicaalumina. The concentration of sulfur in the naphthafeed which can be tolerated is to a very great extent soiely dependentupon the corrosion resistance of the metal from which the piping andreactors are fabricated. For units in which the metal of the piping andreactors is not a highly alloyed, highly corrosion-resistant s eei theupper limit of sulfur concentration is about 20 p.p.rn.

A naphtha or a mixture of naphthas, i.e., straight run naphtha, orcracked naphtha, or a mixture of straight run naphtha and crackednaphtha containing about 1 ppm. of nitrogen and essentially free ofarsenic drawn from a source not shown through pipe by pump Z. Fump L-discharges the naphtha into conduit 3. frs used herein essentially freeof arsenic designates a concentration of arsenic in a ref rrner feedwhich, when said reformer feed is contacted with a bed of reformingcatalyst comprising 0.35 percent platinum by weight, is insufficient todeactivate said catalyst within the life of the catalyst, for exampletwo years, as determined by other factors such as the temperaturerequired to produce a retorrnate having an octane rating of at least(l-,L3 ce), the yield 0f reformatie, and the mechanical strength of thecatalyst. At some point in conduit 3 intermediate to the llischarge ofpump 2 and to heater 5 hydrogen-containing gas, for example, recycle gasfrom conduit d2 is mixed with the feed naphtha in the mol proportionwithin the limits set forth hereinbefore to provide a charge mixture.The charge mixture tiows through conduit 3 at a pressure greater thanthat in the rst reaction stage to coil i in heater 5.

In heater 5 the charge mixture is heated to a reforming temperaturewithin the range orf about 800 to about 1000 F. dependent upon theactivity of the catalyst and the target octane rating of theC5-lreformate to be produced. From heater 5 th heated charge mixtureflows through conduit 6 to first reaction stage vapor inlet 7. Fromvapor inlet the charge mixture tiows into inlet plenum chamber 8.Reaction zones 9, lo and il are in fluid communication t 7ith inletplenum chamber 3 through reaction zone inlets 12, 13 and 14. En thedrawing reaction zone 9 is undergoing regeneration while reaction zones10 and 11 are on-stream. Accordingly, the charge mixture flows frominlet plenum chamber 8 into reaction zones i0 and 11 through reactionzone inlets 13 and i4 respectively.

Reaction zones 9, 10 and 1i are filled with a particleform, solid,reforming catalyst. Presently preferred is a platinum-group metalreforming catalyst, a particularly a platinum metal reforming catalystcomprising about 0.35 to about 0.60 percent by weight platinum and about0.05 to about 0.60 percent by weight chlorine on an alumina support.

The charge mixture tiows downwardly in contact with the reformingcatalyst in reaction zones i0 and lli through reaction zone outlets leand i7 respectiveiy to outlet plenum chamber t3. From outlet plenumchamber 13 the reaction zone efiluents flow as a single vaporous streamto reaction stage vapor outlet i9. From reaction stage vapor outlet 1.9the first reaction stage eiiluent flows through conduit 20 to coil 2l inheater 22.

heater 22 the nrst reaction stage efuent is reheated to a reformingtemperature the saine as, or higher, or lower than the reformingtemperature to which the charge mixture is heated in furnace 5i. Fromheater 22 the reheated r'irst reaction stage effluent ows throughconduit 23 to second reaction stage vapor inlet 2li.

From second reaction stage vapor inlet 2d the reheated first reactionstage effluent or first eiluent flows into second reaction stage inletplenum chamber 25. it will be observed that as illustrated reactionzones 2:6 and 27 are sn-stream while reaction Zone Z3 is beingregenerated.

The reheated rst effluent ows from second reaction stage inlet plenumchamber to reaction zones Z6 and 2'? through reaction zone inlets 29 andSil respectively.

rEhe reheated first eiliuent flows downwardly through reaction zones 25and 27 in contact with the particleform solid reforming catalyst thereinto reaction zone outlets 32 and 33 respectively to outlet plenum chamberln outlet plenum chamber $5 the reaction zone effluents nix to provide areaction stage eliluent, designated second effluent, which flows fromoutlet plenum chamber 35 through reaction stage outlet 36 to conduit 37.The second effluent flows through conduit 37' to coil 3th in furnace 39.

ln furnace 39 the econd eluent is reheated to a reforming temperaturethe same as, or lower, or higher' than the temperature to which thecharge mixture is heated in furnace 5 `and the first effluent is heatedin heater 22. From heater 39 the reheated second eiiluent flows throughconduit dll to the Vapor inlet 41 of the third reaction stage.

From vapor inlet All of the third reaction stage the reheated secondeffluent llows into third reaction stage inlet plenum chamber 42 of thethird reaction stage. lt will be observed that reaction zones 43 and 45are ori-stream and that reaction zone 44 is being regenerated. Frominlet plenum chamber 4-2 the reheated second eflluent flows throughreaction zone inlets lo and l to reaction zones 43 and l5 respectively.

The reheated second effluent flows downwardly through reaction zones 43and d5 in Contact with the particle-form solid reforming catalysttherein. From reaction zones 43 and 45 the reaction zone effluents flowthrough reaction zone outlets 49 and 5i to outlet plenum chamber 52where the reaction zone effluents mix to form the third react-ion stageefliuent. The third reaction stage efdnent flows through third reactionstage vapor outlet '53 to conduit The third reaction stage effluent, nowdesignated third effluent, flows through conduit Sli to cooler 55'. lncooler 35 the temperature of the third eflluent is lowered to that atwhich C4 and heavier hydrocarbons are condensed. When necessary tomaintain a temperature at which C4 heavier hydrocarbons are condensed apart or all of tl e third effluent can by-pass cooler by opening valve56 in conduit 57 through which the by-passed portion of the thirdeiiuent flows to conduit 58 and thence to separator 59. All or thatportion of the third eluent flowing 'through cooler 55 flows throughconduit SS to liquidgas separator 59.

ln liquid-gas separator' 59 the condensed portion of the third effluentis separated from the uncondensed portion of the third efliuent. Theuncondensed portion of the third eilluent comprising C1 to C4hydrocarbons and hydrogen, now designated recycle gas, ows fromseparator through conduit ofi to the suction side of compressor ol.Compressor dl recompresses the recycle gas to a pressure about equal tothat in conduit 3 which, as has been stated hereinbefore, is greaterthan the pressure in the first reaction stage. The repressured recyclegas flows from compressor 6l through conduit 62 to conduit where therecycle gas is mixed with the charge naphtha as described hereinbefore.A portion of the recycle gas about equal to the amount of gas madeduring the reaction is vented through conduit o3 under control of valveto other processes in which a hydrogen-containing gas of the compositionof recycle gas can be used.

The condensed portion of the third effluent comprising C5 and heavierhydrocarbons with some C4 hydrocarbons, new designated reformate, flowsfrom separator 559 through pipe to a stabilizer not shown and theaddition of additives, stored and/or distribution.

As illustrated, one reaction zone in each reaction stage is underregenerating conditions while the other reaction zones in each reactionstage are on-stream, i.e., under reforming conditions. Consequently,separate regeneration piping, compressors, and the like are required forre` vaeration. While one or more of the feed heaters can be piped forheating the rcirculating regeneration gases better flexibility isprovided with an auxiliary furnace for heating the circulatingregenerating gases.

Regeneration of the catalyst in the reaction zones not on-stream isachieved in the manner described hereinafter. lt will be observed bythose skilled in the art that preferably each reaction zone is providedwith an inlet valve and an outlet valve having a tubular stem throughwhich the regeneration gases enter and leave 'the reaction zoneundergoing regeneration. Each of the foregoing tubular valve stems isprovided with a valve by means of which the flow of regenerating gasesinto or out of the respective reaction zone is controlled. Valves of anysuitable construction to achieve these ends can be used. However, it ispresently preferred to use valves having the structure illustrated. TheValves illustrated are of the furnace header plug type closure means ofwhich there are hundreds of thousands in use. The plug is heavy andstiff while the tapered seat is machined into a thin Wall cylinder. Atthe temperatures to which these valves are subjected, the seat isreadily rounded to the shape of the plug by a closing force which can beas little as a stem force of 700 pounds.

Regeneration of theV catalyst in the reaction zone or zones notott-stream is carried out as follows. As illustrated, the catalyst inone reaction zone in each reaction stage is being regenerated. That isto say, inlet valve 66 and outlet valve 69 in the vapor inlet l2 and thevapor outlet l5 respectively of reaction Zone El in the first reactionstage are shown in the closed position isolating reaction zone S' frominlet plenum chamber or manifold 8 and outlet chamber or manifold i8.Similarly., inlet valve 74 in vapor inlet 3l and outlet valve 77 invapor outlet 34 in reaction Zone 2S in the second reaction stage areshown in the closed position. It will also be observed that inlet valve79 and outlet valve 32 in reaction zone la in the third reaction stageare shown in the closed position. The three reaction zones (9, 23 andd4) are ready for the initiation of the regeneration operation. (lt willbe observed that each pair of valves 66 and 65! in reaction zone 9; ofvalves 74 and 77 in reaction zone 28; and of valves 79 and 82 inreaction Zone d4.- serve to isolate the associated reaction zone fromthe associated inlet manifold and outlet manifold.)

lnert gas, eg., nitrogen, flue gas containing less than 5l), andpreferably not more than l, percent carbon monoxide, and the like drawnfrom a source not shown through conduits S4 and 39 (valve 85 open,valves So and 57 closed) by compressor or pump d is pumped throughconduit El? and coil 93 in heater itl-l to purge the reaction zones thecatalyst in which is to be regenerated. The use of hot purge gas ispreferred to avoid cooling `the catalyst bed to be regenerated. Thepurge gas flows from coil 93 into manifold lf-l. From manifold M; aportion of the purge gas flows through conduit 96 in part to conduitlili and in part to conduit 9h (valves lllt and itil. being open). Thebalance of the purge gas flows through conduit 97 (valve 99 open).

The purge gas flows from conduit 97 to reaction zone purge inletmanifold ltl' having branches lilo, and 138 with valves itl?, il@ andlill respectively. he purge gas flows through purge manifold ldd tobranch i103 (valves lll? and lll-ttl closed; valve lll open) and thence,preferablythrough the hollow stem (as described hereinafter) of plugvalve 74, to reaction zone 2S. The purge gas flows downwardly throughreaction zone 28 to plug valve 77 and thence, preferably through thehollow stern of valve 77, to purge outlet manifold branch 112 havingvalve M5. (Valve M6 in purge outlet manifold branch M3 and valve 117 inpurge outlet manifold branch .illbeing closed.) From purge outletmanifold branch MZ the purge gas flows to purge outlet manifold MS. Fromrespectively. Dilfcren al pressure contro epesses purge outlet manifoldllll the purge gas flows to conduit jill@ and thence through conduit 12uto cooler lili. cooler lZl the gas is cooled to about Sil to 1GO P. tocondense any water therein. From cooler lZl the purge gas llows throughconduit 122 to liquid-gas separator i225. ln liquid-gas separator 123the condensed water separates and is Withdrawn in any suitable mannerthrough pipe i214 under control of valve M5. The uncondensed purge gasis vented from separator 123 through conduits ld and T127, valve S7closed and valve Se opened.

Alternatively, the purge gas flows from conduit 57 to manifold liti andbranch M2, and thence through the hollow stern of plug valve 77 toreaction zone 28. From valve 7'7 the purge gas iiows upwardly throughreaction zone Ztl to plug valve 7d, through the hollow stern thereof tomanifold branch llt, manifold lll and suitable alternative piping tocooler T121 and liquid-gas separator in a similar manner the balance ofthe purge gas ilo f through manifold branch or conduit 96 to conduitsand lllZ. lFrom conduit the purge gas flows thrcuigA purge inletmanifold 156 having branches E23, i219 anu i3d, flow to which iscontrolled by valves 1.3i, i323 and 133 respectively. Similarly, thepurge gas flows through conduit im to purge inlet manifold MBS havingbranches M2, 143 and 44, flow to which is controlled by valves MS, 146and 147 respectively.

Returning to the description of the flow of purge gas through conduit 98and purge inlet manifold 15o, since reaction zone 9 is to be purged andthe catalyst therein regenerated valves 132 and 133 are closed and valvell in purge inlet manifold branch M8 is open. The purge gas ows throughmanifold branch 128 and preferably the hollow stem of valve 6o toreaction zone 9'. The purge gas flows downwardly through reaction zone 9to valve 69, preferably through the hollow stern thereof, to purgeoutlet manifold branch 134 having open valve 37 to purge outlet man ld(it will be observed that purge outlet manifold rait' is provided withmanifold branches 13S and 3.36 having closed valves 133 and i3?preferably connected with the hollow stems of plug valves 'd and '7lrespectively.) From purge outlet manifold 'the purge gas liows throughconduit lt to conduits flf and lfi, cooler 121, conduit 122 andseparator 123. in separator M3 the uncondensed purge gas is ventedthrough conduits 325 and 3l27 and the condensate drawn oi`r` in anysuitable manner as previously described with reference to the purging ofreaction Zone 23.

Fl`he purge gas flows from conduit l?. to purge inlet manifold im havingbranches and Flow s to these branches is controlled by valves 145, and."1 respectively. nince the catalyst in reaction zone dit is to beregenerated valves M5 and :M7 are closed and valve if open. rEhe purgegas flows from purge manifold to branch lill-3 and then, preferably,through the hollow stern of plug valve '79 to reaction zone The purgegas iiows downwardly through reaction Zone 4d, preferably to tue hollowstein of plug valve and thence to purge outlet manifold branch lice.With valve open the purge gas llows from branch to purge outlet manifoldidd.

(it will be observed that reaction Zones d5 and a5 are connectedpreferably through the hollow Sterns of plug valves 3l and respectivelyto purge outlet manifold branches i' and `r'llov.' through these purgeoutlet manifold branches is controlled respectively by valves and 153.)From purge outlet manifold the purge gas flows through conduits 1.55 andl2@ to cooler i, conduit i212, and separator i133. The uncondensed gasis vented rorn` separator E23 through conduits E26 E27. Ccndensate isdrained in a suitable manner through pipe "24 under control of valve M5.

lt will be observed that each reaction stf ge a diierential pressurecontroller l5.'

the conventional type and is in fluid connecti inlet manifold 2.5 andpurge outlet manifold ential pressure controller 155 of any suitabletype is in: fluid connection 'with vapor inlet manifold l and purgeoutlet manifold l lil. Differential pressure controller i539 similar tocontrollers i557 and is in uid connection ith vapor inlet manifold d2and purge outlet manifold As is welltnov/n to those skilled in the artditerential pressure controllers are means which, since a predetermineddifference in pressure is to be maintained between two zones, controlthe pressure of vapors entering one zone to 'ain a predeterminedpressure differential be-V tween that zone the other. Thus, differentialpres sure controllers 157, and l5@ operate to maintain a greaterpressure in the reaction zone undergoing regeneration than in the varorinlet manifold of the reaction stage of the aforesaid reaction zone is apart. Prete ably, the pressure differential is of the order of about 5psi. to about 25 p.s.i. That is to say, for example, the pressure inreaction zone 2i; is maintained about 5 psi. to about 25 psi. higherthan the pressure in vapor inlet manifold Z5. T Lus, the pressure inpurge manifold liti is about 265 psi. and the pressure in vapor inletmanifold is about psi.

By maintaining the pressure in the reaction Zone undergoing regenerationabout 5 psi. to about Z5 psi. above the pressure in the associated vaporinlet manifold an f leakage of gas is from the reaction Zone into thevapor inlet manifold From this it follows that the concentration ofoxygen in the mixture of hydrocarbon vapors and rydrogen will be belowthe flash or explosion concentration at the existing temperatures andpressures.

Purge gas is pumped through each reaction zone the yst in which is to beregenerated until a volume of puree gas has passed through the aforesaidreaction Zone which is at least equal to twice the volume of the emptyreaction Zone. When that volume of inert purge gas, eg, flue gas,nitrogen or the like, has passed through each reaction zone the catalystin which is to be regener` ated, the passage of inert gas containingoxygen through the purged reaction Zone(s\ is started.

Accordingly, after purging as described hereinbefore, valve l is openedand valves S5 and $6 are closed and the inert gas circulated through thereaction zones the catalyst in which is to be regenerated and the heateri9@ until the temperature in each zone under regeneration is about 725to about 750 F. When the aforesaid temper ature is reached in each ofreaction Zones 9, 28 and oxygen or oxygen-containing gas, eg., air, isintroduced through conduit 12.7 under control of valve 6 into thecirculating stream of heated inert gas. The oxygen con. centration ofthe circulating gases is increased to not above l percent while the peaktemperature in the catalyst bed in each of reaction Zones 9, 23 and eddue to combustion of the carbonaceous deposit on the catalyst ismaintained below about 875 F. The gas from the reaction zones 9, 2S andle ows to conduit l2@ and cooler 1211. where the `circulating gas iscooled to below about 80 F. at p.s.i.g. to maintain the dew point of thecirculating not greater than 80 F. at lili) p.s.i.g. When oxygen isdetected in the regeneration gases owing from any reaction zone theregeneration of the catalyst in that Zone is completed. The reactionzones in which the regeneration is completed are then ready for purgingand putting ori-stream. 'ilse reaction zones after regeneration of thecatalyst are pui ed as before. That is to say, valve d? is closed, valve555 is opened and inert gas drawn from a source not shown throughconduit Se is circulated around heater lofi through the reaction zonesin which regeneration of the catalyst has been completed to separatorand the uncondensed gas vented through conduits 32o and l2? until anamount of inert purge gas at least equal to about twice the volume ofthe reaction zone(s} in which regeneration been completed has passedrough the zone(s). vvalves lil, lli Bi, 137, lilo and hid, Los are thenclosed an valves 66, 69, 7d, 77, 75* and 82 are opened to place reactionzones 9, 28 and 44 on-stream again. Thereafter, one or more of the otherreaction zones 1d, 11, 26, 27, d3 and 45, but usually not more than onereaction zone in each reaction stage, is prepared for regeneration. itwill be observed that while the catalyst in one or more reaction zonesis being regenerated the other reaction zones are on-stream.

While the present invention has been described hereinbefore inconjunction with the use of a plurality of reactors each providing onereaction stave and a plurality of reaction zones in each reaction stage,it is preferred to employ a single reactor having a plurality ofreaction stages, say tive, and each reaction stage having a plurality ofreaction zones, say three, as illustrated in FIGURES 2, 3a, 3b, 4, 5, 6and 7.

in the preferred method of reforming in accordance with the principlesof the present invention a single reactor having a plurality of reactionstages is employed. Each reaction stage has a plurality of reactionzones in selected tluid communication with a charge manifold or vaporinlet manifold common to all of the reaction zones in that stage and inselected fluid communication with an effluent manifold or vapor outletmanifold common to all of the reaction zones in that reaction stage. Thereactor is valved to provide for regenerating at least one reaction zonewhilst the other reaction zones in all reaction stages are ort-stream.

l'n contrast to the embodiment illustrated in FIGURE l the catalyst inonly one of the fifteen reaction zones illustrated is shown undergoingregeneration. This illusstrates the great flexibility of the method andapparatus of the present invention. .hat is to say, the catalyst in onlyone of the reacton Zones of all of the reaction zones in all of thereaction stages can be undergoing regeneration or the catalyst in onereaction Zone in each reaction stage can be undergoing regeneration orthe catalyst in one reaction zone in more than one but less than allreaction stages can be undergoing regeneration whilst the other reactionzones are on-stream. The order in which the catalyst in the reactionzones is regenerated is not fixed but dependent upon the condition ofthe catalyst. However7 usually for practical reasons of operatingsirnplicity a sequence, varying with local management, is establshiedand followed. As shown in FIGURES 3a and 3b the catalyst in reactionzone 1c only is undergoing regeneration. However, it is to be understoodthat under other local conditions the catalyst reaction Zone could beundergoing regen-eration. Thus, for example, dependent upon localconditions it can be found that regeneration of the catalyst in reactionzone c will be required` iirst.

in the presently preferred form the multi-reaction stage, multi-reactionzone reactor comprises a horizontal cylindrical tank having a shellsupported in any suitable manner (El URES 2 and 3u and 3b). rhe reactoris provided with a plurality of vapor inlets 151 each one of which is inHuid communication with the charge manifold or vapor inlet manifold ofonly one reaction stage. The reactor is also provided with a pluralityof vapor outlets 152 each one of which is in fluid communication withthe effluent manifoldr or vapor outlet manifold of only one reactionstage. The reactor is provided with a liner 153 spaced from shell 15dtoprotect the shell during regeneration and to provide more unform shelltemperature and process operation by circulation of the outlet vaporsbetween the shell and the liner. To prevent coniniingling of thereaction products circulating between liner and shell 15d with reactantvapors, it is presently preferred to mount a baffle 153351 horizontallyin a vapor-tight manner between shell 15@ and liner 153 (FGURE 2),between shell 15h and plate l7S (FIGURE 3a), and between shell 150l andplate 179 (FIGURE 3b). (in Fi-GURE 7 the baffle 25de is the equivalentof bafe in FIGURES 30.' and 3b.) Liner 155 is rigidly rounted on.conduits l5@ (FlGURE 2) through which the hollow stems of the plug valveclosure means of Cit l@ each reaction zone extend as is describedhereinafter. As shown more in detail in FIGURE 2, along the longitudinalmedian line of the bottom of liner 153 at a point in each reaction zonea vapor outlet 155 serving as a valve seat is mounted on the shell sideof the periphery of liner 153. A plenum chamber is formed between thelower section of the shell and the bottom of the liner. A similar plenumchamber is formed between the upper section of liner 153 and a pluralityof arcuate horizontal partitions 156.

Concentric with each vapor outlet 155 is a conduit 157 mounted in shell15@ and making a huid-tight joint therewith as by welding. To strengthenthe shell arcuate reinforcing members 158 and 159 are mounted as bywelding to the outer periphery of the shell in the region of conduits154 and 157 and vapor inlets 151 and vapor outlets 152.

Between each conduit 154i and arcuate horizontal partition 156 aplurality of spacing rods 160- is rigidly mounted (FIGURE 2).Preferably' the spacing rods ar spaced 90 degrees apart and concentricwith the vertical axis of the conduit 154. A plurality of spacing rods172 preferably spaced apart 90 degrees is rigidly mounted between thebottom of liner 153 and conduits 157. Preferably the spacing rods areconcentric with the vertical axis of conduit 157.

Conduits 154 and 157 are flanged and provided with plates 151 and 16Erespectively. Plates 161 and M2 are removably mounted in a fluid-tightmanner by a plurality of bolts and associated nuts i163 and 164respectively.

Concentric with the vertical axis of each of conduits 154 a thin walledcylinder v165 is mounted in a duid-tight manner on arcuate horizontalpartition 156. Cylinder t55 serves as a vapor inlet to the associatedreaction Zone as well as a valve seat for plug 166.

Each of plates 161 is provided with a plug bored to provide a sliding htwith hollow ste- 167 on which plug 16o is mounted. Mounted in ahuid-tight manner on each of plates 161 concentric with the verticalaxis of the hollow stern 1o? of the plug valve is a sleeve 16d withinwhich the stern of the plug valve is free to be raised or lowered inresponse to the action of the conventional hand wheel 196 (FIGURE 4).

Similarly, each of plates lo?. is bored to provide a sliding lit withhollow stern on which plug 17d is mounted. Mounted in a duid-tightmanner on each of plates 162 concentric with the vertical axis of thehollow stern 159 of the plug valve is a sleeve 1711 within which thestem of tlre plug valve is free to be raised or lowered in response tothe revolution of the conventional hand wheel.

A plurality of plate supports, columns, pillars, 173 are rigidly mountedon the bottom of liner 153 in each reaction zone'. A fo-ramincuscatalyst bed support, preferably a perforated plate 174 having aperiphery complementing the periphery of a reaction zone is rigidlymounted on the aforesaid plate supports in each reaction zone. A wiremesh 175 having openings small enough to preclude passage ofsubstantially all of the particles of particulate solid of the reactionZone is mounted on the upper surface of plate 17d.

The cylinder formed between arcuate horizontal partition 156 and reactorliner 153 is sealed at the ends thereof by plate 17 and i79 (FIGURES 3aand 3b). The space within the cylinder formed by partition 156 and liner153 is divided into a plurality of reaction stages (tive areillustrated) by vertical arcuate plates Mill. Each of plates 1S@ isrigidly mounted in a fluid-tight manner on the inner periphery ofreactor shell 15@ in any suitable manner as by welding. Fuild-tightjoints are made in any suitable manner between plates and the horizontalarcuate partition 156 and liner 153. Each reaction stage is divided intoa plurality of reaction zones (three are illustrated) by verticalarcuate plates 181.. Vertical arcuate plates 181 are rigidly mounted ina fluid-tight manner between horizontal arcuate partition. 156 and lliner i?, as by welding to the liner 153 and to the horizontal arcuatepartition o.

Reference is made to FlGURES 4, 5 and 6 for the details of the reactionzone vapor inlet valves and the reaction zone outlet valves. While anymechanism where by a reaction Zone can be selectively isolated from boththe vapor inlet manifold and the vapor outlet manifold can be employedand while any means for introducing and removing regenerating gases fromthe isolated reaction Zones can be employed it is preferred to employthe mechanism illustrated. The rising stern plug valves illustratedserve not only to isolate the respective reaction zones from the vaporinlet manifolds but also serve as ymeans for introducing and withdrawingthe regenerating gases from the isolated reaction Zones.

The rising stern valve illustrated is a modification of the conventionalrising stern valve having a conventional lantern-type stuffing box. Thatis to say, the stem of a conventional valve is replaced with a pipe, say1.5 inches in diameter, which serves to introduce regenerating gasesinto the isolated reaction zone served by the valve at the top of thereaction zone and to withdraw regenerating gases from the isolatedreaction Zone through the valve at the bottom of the isolated reactionzone.

The valve consists of cylinder 165 machined to a thickness that when theplug 166 is yforced into the cylinder M5 the cylinder readily isdeformed at the environmental temperatures to conform with the peripheryof plug 166, preferably both the plug 166 and the cylinder 165 aretapered. The pipe 167 which replaces the stern of the conventionalrising stern valves runs vertically through the packing gland 156 andturns in a convenient angle 1&7 at the point where the stem in a normalrising stem valve is threaded. The angle at which the rigidly mountedpiping through which the regenerating gases are brought to or withdrawnfrom the valve is that most convenient depending upon local conditions.Concentric with the stern pipe 157 there is welded to the top of the L athreaded stub 188 to pass through the yoke 1%9 to provide for verticalmovement of the pipe lo? and its attached valve plug 166 in response tothe revolution of hand wheel wil. To provide for movement of pipe 167vertically, spacer blocks 191 are inserted between yoke 189 and flange192 of pipe 193. In the region of the lower end of pipe 1% an annularplate @d having an internal diameter substantially that of stem pipe 167to provide a sliding fit therewith is mounted on the internal eripheryof pipe w3 to provide a rigid surface against which the packing 262 ofpacking gland 186 can bear. Packing follower 195 is movably mounted inany suitable rnanner to subject the packing 2492 to compression.

FEGURE 5 is a cross-section of plug loo, valve seat and reaction zonevapor inlet 165, which are similar in structure to plug i7@ and valveseat and reaction zone vapor outlet 155, showing the tapered form of theplugs and the valve seats.

FIGURE 6 is a cross-section of an alternate method of mounting the valveseats 155 and 65. An annulus E96 is rigidly mounted as by welding onhorizontal arcuate partition 156 to provide a vapor inlet for eachreaction zone. A similar annulus is mounted on the shell side of thebottom section of liner lST3 to provide a reaction zone vapor outlet. Onthe shell side' of annulus 1% a plurality of bolts 197 is rigidlymounted. A thin-walled cylinder 193 machined to receive the tapered pluglo@ of the valve and having iiange i599 rests on annulus 196. The innerdiameter of cylinder 98 is substantially that of the inner diameter ofannulus 196. Flange 1.99 has a width substantially equal to the distancebetween the outer periphery of cylinder 193 and bolts 23.97. The flange199 is of suitable thickness to resist massive deformation from thepressure of spacers 2d@ when nuts Zilli are turned down on bolts 197 tohold cylinder 198 rigidly in position.

The single reactor shown in FIGURES 3a and 3b like l the reactors orreaction stages shown in FGURE 1 is provided with a differentialpressure controller 24% to maintain a substantially constant diterencein pressure between the top of the Zone or Zones in which regeneration othe catalyst is taking place and the reaction stage vapor inlet plenumchamber or manifold. The pressure at the top of the reaction Zone orZones in which the catalyst is being regenerated is maintained at 5 to25, preferably 5 to l0, pounds per square inch above the pressure in thecontiguous reaction stage vapor inlet plenum chamber or manifold. Thus,considering the first reaction stage numbering from the left in 3a and3b only for purposes of illustration, whilst charge mixture vapors enterthe first reaction stage vapor inlet manifold through vapor inlet 151iand first reaction stage effluent flows from iirst reaction stageeffluent manifold Zta through efliuent outlet i523, inert gas such asflue gas hows through conduit 2d?) to conduit 2de having branches 7.65,2%, 267, etc. and by-pass tlti. Each of branches 2h55, 2de and 22%7 isprovided respectively with block valves Ztl@ and 2id, 212 and 213, and215 and Silo. These valves ensure that when the reaction zone with whichthe controlled branch is in fluid communication is ori-stream thereshall be no leakage of regenerating gas into, and no leakage of reactantvapors from the reaction Zone. Drain valves Zilli, 2id, and 217 provide`for venting any gas which leaks past either of the associated blockvalves.

Each reaction Zone is provided with a regenerating gas outlet conduitLS, 23l9 and 22d. Each regenerating gas outlet conduit is provided withblock valves respectively 221 and 222, 224i4 and 225, and 227 and 223which ensure that there shall be no leakage from or to the associatedreaction zone when the reaction zone is ori-stream. Drain valves 223,226 and 229 located on outlet conduits 213, 219 and 22@ respectivelyprovide for venting any gas that leaks past the closed block valves withwhich the drain valve is associated.

lt will he observed that the ditferential pressure controller 2do ofconventional design is connected with inert gas conduit 203, pressuresensing conduit 23@ and control valve 231 located in regenerating gasoutlet main 232. (Valves 233 and 234 are block valves manually operatedas is by-pass valve-235 for use in emergency.)

Pressure sensing conduit 23d is provided with a branch 2236 in iiuidcommunication with each reaction stage vapor inlet manifold. Each branch23d is provided with block valves 237 and 238 which ensure that when allreaction zones in any one reaction stage are ori-stream there shall beno leakage from or to tie associated reaction stage vapor inletmanifold. vvalve 23@ provides for venting any leakage past valves 237and 238.

The differential pressure controller operates to maintain a pressureabove the bed of catalyst in the zone under regeneration at least 5 butpreferably not more than about l0 p.s.i. (pounds per square inch)greater than the pressure in the associated reaction stage vapor inletmanifold. Since there is a pressure drop between conduit 203 and thereaction zone under regeneration of about 20 to 25 p.s.i., it `followsthat the pressure in conduit 20? is about 25 to about 35 p.s.i. higherthan the pressure in the reaction stage vapor inlet manifold.

As illustrated, reaction Zone C in the irst reaction stage is the onlyreaction Zone in the regeneration portion of the cycle. Consequently,all of the inert gas conduit .p 'branch valves except valves Zie", andZie in branch 2d? are closed. Valves 215 and 2id are open but drainvalve 2ll7 is closed. All of the valves in the regenerating outletbranches except valves 227 and 223 in branch 2.2i) are closed. Valves227 and 228 are open while drain valve 2.29 is closed. Valves 233 and234- are open but valve 235 is closed.

By maintaining a pressure in the reaction zone in the regenerationportion `of the cycle higher than the pressure in the associatedreaction stage vapor inlet manifold at all times, the direction of flowof any leakage at the viirst bed of inert solid.

reaction zone vapor inlet valve must be in the direction of the reactionstage vapor inlet manifold. Since the relative volumes of gas flowingthrough a reaction zone under regeneration and the volume of gas flowingthrough the associated vapor inlet manifold are in the ratio of about lto 100, it is manifest that even where the regenerating gases containpercent by volume of oxygen and 5 to l0() percent of the regeneratinggases leak into the reaction stage vapor inlet manifold the mixture ofreactant vapors and regenerating gas would contain only about 1/000percent oxygen` a concentration far below the minimum required for anexplosive mixture.

To illustrate the method of reforming of the present invention employinga single reactor having a plurality of reaction stages, each of whichhas a plurality of reaction Zones wherein the catalyst in at least onereaction Zone but not more than one reaction zone in any reaction stageis being regenerated whilst the other reaction zones are on-stream thehow-sheet FIGURE 7 has been provided. The single, horizontal,substantially cylindrical, reactor o has elliptical ends 251 and 252. Aliner 253 substantially the same as liner 153 in FIGURE 2 is rigidlymounted in reactor 250 spaced apart from the shell to provide forcirculation of the reaction product gases and vapors between the shelland the liner. Horizontal arcuate partition 2541 is the same aspartition 156 in FIGURE 2. End plates 255 and 256 are mounted on liner253 and partition 254i as in FIGURES 3a and 3b. The reactor is providedwith a plurality of vapor inlets 257, 258 and 259 in fluid communicationwith vapor inlet manifolds 261i, 261 and 262. The reactor is providedwith a plurality of vapor outlets 263, 264 and 265 in fluidcommunication with vapor outlet manifolds 266, 267 and 268.

The space between horizontal arcuate partition 254, liner 253 and endplates 255 and 256 is divided into a plurality (three shown) `ofreaction stages by vertical partition 269. Each reaction stage isdivided into a plurality of reaction zones by vertical partitions 270 toprovide reaction zones la, Ib, ic, lla, Hb, llc, lIlfz, IlIb and lllc.Each reaction zone is provided with a vapor inlet providing fluidcommunication between the vapor inlet manifold and the reaction zone.Each vapor inlet also serves as a seat for the plug. The vapor inlet andthe plug forming reaction zone vapor inlet valves are designated 271,272, 273, 274, 275, 276, 277, 273 and 279. Each reaction zone isprovided with a similar vapor outlet and valve 23?, 231, 282, 233, 284,285, 286, 287 and 288 providing fluid communication between the reactionZones and the respective vapor outlet manifolds.

A vapor-solids separator 229 is mounted over each reaction zone vaporoutlet as described in conjunction ith FIGURE 2. in charging eachreaction zone with catalyst a bed of coarse particles, i.e., aboutthree-fourths of an inch in diameter, of an inert solid such as alundurnis placed on plate 174 (FIGURE 2). Two additional beds of successivelyiiner particles of inert solid is placed upon the The catalyst particlesare then placed upon the bed of inert solid particles. Preferably, oneto three beds of successively liner particles of inert solid such asalundurn are placed upon each bed of catalyst.

As shown in lGURE 7 all of the reaction Zones in all of the reactionstages except reaction zone In are onstream. rf'hat is to say, as shownin FIGURE 7, onlythe catalyst in reaction Zone la is being regenerated.(It is to be understood that the catalyst in any of the reaction zonesother than la but not more than one reaction zone in any one reactionstage could be shown as undergoing regeneration.)

in describing the present method of reforming in conjunction with FIGURE7, the flow of vapors and gases through the heaters and reaction Zoneswhich are on-stream rst will be traced and then the ow of gases Kduringthe regeneration of the catalyst in a single reaction zone, zone la,will be traced.

Those skilled in the art will understand that for simplicity variousheat exchangers have been omitted from the drawing FEGURE 7 and thefollowing description.

A straight-run naphtha, a catalytically cracked naphtha, a thermallycracked naphtha, a mixture of two or more of the foregoing, or of one ormore of the fractions of one or more of the foregoing naphthascontaining not more than innocuous concentrations of catalyst poisons isthe feed to the reactorillustrated in FiGURE 7. The naphtha preferablyis reformed in the presence of a platinum-group metal reforming catalystsuch as a catalyst comprising about 0.1 to about 2.0 percent by weightof platinum and about 0.1 to about 0.8 percent by weight yof halogen,for example chlorine, on a support comprising a refractory oxide such asalumina under the following reaction conditions dependent upon theactivity of the catalyst and the required octane rating of the C5 andheavier reformate.

Reaction presure, p.s.i.g l5 to 500 Reaction temperature, F 809 to 1000Liquid hourly space velocity, v./hr./v 0.3 to 5 Hydrogen-to-naphtha molratio 3:1 to 10:1

Accordingly, naphtha feed containing not more than innocuousconcentrations of catalyst poisons, eg., not more than about l ppm. `ofnitrogen and essentially free of arsenic as deiined hereinbefore ispumped by a pump not shown from a source not shown at a pressure greaterthan the pressure in reactor 25) through conduit 2%. At some point inconduit 2% intermediate to the naphtha pump not shown and to heater 291hydrogen-containing gas, such as recycle gas, drawn from a liquid-gasseparator by a compressor and pumped by the aforesaid compressor throughconduit 292 at a pressure substantially that in conduit 2ML is mixedwith the naphtha feed in a mol ratio within the range set forthhereinbefore to form a charge mixture.

The charge mixture flows through conduit 29d to coil 293 in heater 291.In naphtha furnace 291 the charge mixture is heated to a temperaturewithin the limits set forth hereinbefore. The heated charge mixture howsfrom heater 291 through conduit 294 to vapo-r inlet 257 of vapor inletmanifold 26h serving the first reaction stage having reaction zones la,lb and Ic. It will be observed that valve 271 is shown to be closed..Accordingly, the charge mixture ilows from vapor inlet manifold 260through valve 2A 2 into reaction zone Ib and through valve 273 intoreaction zone lc.

ln reaction zones lb and lc the charge mixture nov/s downwardly incontact with the particle-form solid reforming catalyst. The eilluent ofreaction zone lb flows through effluent valve 281 into eiiluentlmanifold 266. The effluent of reaction zone Ic flows through valve 282into effluent manifold 26o where the eflluent of reaction Zone le mixeswith the effluent of reaction Zone lb to form the rst eluent. The firstetlluent flows from elfluent manifold 266 through eflluent vapor outlet263 to conduit 295'. The first effluent lows through conduit 295 to coil296 in heater or naphtha reheat furnace 297.

ln naphtha reheat furnace 297 the rst ellluent is reheated to atemperature within the range set forth hereinbefore. The reheated firsteffluent ilows through conduit 298 to second reaction stage vapor inlet25S and through vapor inlet 253 to second stage vapor inlet manifold2.6i serving reaction zones Ila, 1lb and lic. lt will be observed thatall of the reaction Zones Ila, Hb and lc are shown to be on-stream.Consequently, the reheated first effluent flows from second stage vaporinlet manifold 2e1 in part through valve 274.` to reaction Zone lla, inpart through valve 275 to reaction zone Hb, and in part through valve276 to reaction zone Hc.

The reheated first effluent flows downwardly through reaction zones lla,llb and Ile in intimate Contact with the catalyst therein to eluentvalves 233, ne and respectively. The etlluents from the three reactionZones mix in effluent manifold 267 to form the second eflluent. Thesecond effluent ows from efiluent manifold 267 through effluent vapor`outlet 266` to conduit The second effluent flo-ws through conduit 2% tocoil 304i in reheat furnace 361.

ln reheat furnace 3L' the second eiluent is reheated to a temperaturewithin the range set forth hereinbefore. The reheated second eluentflows from furnace 364i through conduit 3F32 to vapor inlet The reheatedsecond effluent flows through vapor inlet 259' to third reaction stagevapor inlet manifold 262 serving reaction Zones lila, lllb and ille.From third reaction stage vapor inlet manifold 262 the reheated secondcflluent flows in part through valve 277 into reaction zone illu, inpart through valve 273 into reaction zone Elib, and in part throughvalve 279 into reaction zone lllc.

ri'he reheated second effluent hows downwardly in intimate contact withthe reforming catalyst therein i through reaction Zones lila, lilb andille to effluent valves 236, 237 and 28S respectively. rl-he etlluentsof these three reaction zones flow into and mix in effluent manifold 263to form the third or final effluent. The final effluent ows fromeffluent manifold 263 through vapor outlet 265 and conduit 363 to acooler 3M- w-here the final effluent is cooled to Ia temperature atwhich C4 and heavier hydrocarbons are condensed under the existingpressure. From cooler 36d the nal effluent ows through conduit 365 to aliquid-gas separator 306 where the condensed C5 and heavier hydrocarbonstogether with some C4 hydrocarbons are separated from the uncondenscdhydrogen and light hydrocarbons of the final effluent. The uncondensedhydrogen and light hydrocarbons, at least in part, is the recycle gaswhich is recompressed and pumped through conduit 292 to mix with freshfeed in conduit 296. Recycle gas in excess of that required in reactor256* is diverted through conduit 333 to other processes utilizinghydrogen-containing gas of this composition. The condensed C4 andlheavier hydrocarbons designated reformate flow from ythe separator 366through pipe 367 to stabilization, addition of additives such as TEL,anti-rust agents, anti-icing agents, etc., storage, blending, aud/ordistribution.

Those skilled in the art will understand that various heat exchangers,coolers, fractionators and the like have been omitted from theillustrative drawing and the description since they are not a part ofthis invention, to simplify the drawing, and are well-known to thoseskilled in the art.

While reaction Zones lb, lc, ilu, llb, llc, illu, illb, and lilo havebeen on-stream and described hereinbefore, the catalyst in reaction zonela is being regenerated. lt is to be observed that the catalyst in anyone reaction Zone, but not more than one reaction Zone in one reactionstage, can he undergoing regeneration.

Regeneration of the catalyst in reaction zone la is carried out asfollows.

it will be observed that each reaction stage is in fluid communicationwith a regenerating gas main 3th. Each reaction zone is in controlledfluid communication with the regenerating gas main 3l@` through the stemof the vapor inlet valve of a reaction zone in that reaction stage andla valved pipe. Thus, when the reaction Zone inlet valve in any reactionZone is closed and that reaction zone isolated from its associated inletmanifold, the isolated reaction zone is in controlled, i.e., valved,cornmunication with the regenerating gas main 3l@ through lthe closedreaction zone inlet valve, and one of the branches of the regeneratinggas main designated 3ll'll, 3l2, 3-l3, 3M, 315, 3l6, 317, 33H18 and319', each having two block valves for simplicity indicated by singlevalves 32h, 321i, 322, 323, 324i-, 325, 326, 327 and 328 respectively.

Each reaction Zone is in controlled lluid communication with the wastegas main 3.0- when the reaction zone etiiuent valve is closed throughthe valve stem of the closed reaction zone effluent valve and a wastegas main branch. Thus, when the reaction zone effluent valve in anyreaction Zone is closed and that reaction Zone isolated from itsassociated effluent manifold, the isolated reaction zone is incontrolled, i.e., valved, communication with the waste gas main 329'through the closed reaction zone effluent valve, and `one of the wastegas main branches designated 33o through 333 each having two blockvalves, for simplicity, indicated by Single valves 339' through 347.

Any inert gas, such as llue gas, nitrogen, etc. can be used as a purgegas and as a carrier or diluent for the oxygen required for combustionof the carbonaceous deposit or coke on the catalyst. It is presentlypreferred to use flue gas as the purge gas and as the carrier or diluentof the oxygen-containing gas, usually air, although baffled oxygen canbe substituted in part or entirely for air, required for the combustionof the coke.

lFlue gas of controlled composition is readily produced in the mannerillustrated in FIGURE 8. Fluid fuel, for example refinery gas, fuel oil,natural gas, etc., flows from a source not shown through conduit 348 toa burner(s) not shown in flue gas generator 350. Air for combustion ofthe fuel to provide a flue gas substantially devoid of free oxygen flowsthrough conduit 349 to the burner(s) in flue gas generator 356. The fuelis burned in the generator and flows therefrom through stack 351. Amajor portion, about percent of the flue gas produced is diverted fromstack 351 through conduit 352 to scrubber 353. The ue gas entersscrubber 353 at a point in the region of the bottom thereof. Waterflowing from a source not shown through pipe 354 enters the scrubber ata point in the region of the top thereof, flows downwardly therethroughand leaves the scrubber through pipe 355. The flue gas flows upwardlythrough the column of Water which removes water-soluble contaminantssuch as oxides of sulfur from the llue gas. The scrubbed ue gas flowsfrom scrub-ber 353 through conduits 356 and 361 to the suction side ofcompressor 362. At a point intermediate to scrubber 353 and compressor362 oxygen-containing gas, usually air, flowing through conduit 357having valve 358 is mixed with the scrubbed flue gas.

Valve 353 is opened or closed to maintain a predetermined concentrationof oxygen in the llue gas as sensed by oxygen controller 359 throughlead 360. The flue gas, substantially devoid of oxygen when used as apurge gas and having a controlled, predetermined concentration of oxygenwhen coke is being burned, flows through conduit 361 to the suction sideof compressor 362. The compressed gas flows through conduit 363 toscrubber 364. The oxygen-containing flue gas flows upwardly in scrubber361i through a descending column of water which water enters scrubber364 through pip-e 365 and leaves scrubber 364i through pipe 366.

The washed oxygen-containing flue gas ows from scrubber 365:- throughconduit 379 to conduit 367. Drying of the ue gas whether used as a purgegas or used as a diluent in conjunction with oxygen-containing gas isnecessary. For this purpose it is preferred to dry the gas with a bed ofparticle-form solid desiccant such as alumina zeolites commonlydesignated molecular sieve material or the like. Since the static bed ofdesiccant must be regenerated to preclude interruption of the ow ofdried llue gas, two beds of desiccant are provided. While one bed ofdesiccant is on-stream the other is being regenerated. Accordingly,assuming that the desiccant in drier 371 is being regenerated, thendrier 372 is onstream. That is to say, valve 369 in conduit 368 andvalve 37d in conduit 373 are closed. Valve 371 in conduit 373 and valve376 in conduit 375 are open. The llue gas with or without added oxygenflows from conduit 367 through conduit 370, drier 372, and conduit 375to conduit 377. From the drier the Hue gas ows through conduit 377 tocoil 378 in due gas generator 350. In coil 378 the dried ue gas isheated to about 700 to about 850 F. From coil 378 the heated llue gasflows through the regenerating gas main 310 to the branch of theregenerating gas manifold which is connected to the stem of the reactionzone inlet valve which is closed.

As shown in FIGURE 7, the catalyst in reaction zone Ia only is to beregenerated. Accordingly, while reactants ow from vapor inlet 294 tovapor inlet manifold 260 and thence into reaction Zones Ib and Ic, thecatalyst in reaction zone Ia is regenerated. To regenerate the catalystin any reaction Zone such as reaction zone Ia, the reaction zone vaporinlet valve and the reaction zone effluent valve are closed isolatingthe reaction zone from the vapor inlet manifold and the effluentmanifold with which the reaction zone is associated.

lFlue gas substantially devoid of oxygen is circulated from generator350 to regenerating gas main 3l@ as described hereinbefore and thencethrough conduit 332 (valve 3ST open) to waste gas main 329 until it iscertain that the differential pressure controller 384 is functioning tomaintain a pressure in reaction zone Ia above the bed of catalyst aboutto about 25, preferably 5 to l0 p.s.i. higher than the pressure in vaporinlet manifold 260. When differential pressure controller- 334i is sofunctioning plug valve 27T is closed, valve 381 is slowly closed whilevalve 320 is opened and flue gas substantially devoid of free oxygenflows from regenerating gas main 310 through branch 311, the stem ofplug valve 27T into and through reaction zone Ia to efliuent valve 280and effluent manifold 266. In effluent manifold 266 the liu-e gas andhydrocarbons and hydrogen purged from reaction zone Ia mix with theeffluent of reaction zones Ib and Ic and flow as a rst eluent throughconduit 295 to coil 296 as previously described in conjunction with thedescription of the flow of the first effluent.

After a volume of flue gas equal to about two to six times the volume ofreaction zone Ia has passed through reaction zone la, the reaction zoneis purged. Plug valve 280 is then closed and valve 339 in branch 3313 ofwaste gas main 329 is opened isolating reaction zone Ia from effluentmanifold 256'. With reaction Zone Ia isolated from both inlet manifold260 and effluent manifold 266 flue gas substantially devoid of oxygen ispassed through reaction zone Ict to waste gas main 329 for about thirtyminutes more, i.e., about 2 to 6 volumes additional based upon thevolume of reaction zone Ia. Thereafter, oxyen or oxygen-containing gasis mixed with the flue gas in conduit 356 under regulation by oxygencontroller 359 to provide a concentration of oxygen in the gas inregenerating gas main 3l@ of about 0.5 percent by volume.

When combustion is initiated in the bed of catalyst in reaction zone Iathe concentration of oxygen in the flue gas is gradually raised to notmore than about 1.0 percent by volume while limiting the temperature inthe catalyst bed to a maximum of about 850 F. when the temperature ofthe gas in branch 330 ofv the waste gas main is not substantially higherthan the temperature of the gas in regenerating gas main 3F10 or whenoxygen is detected in the gas entering the waste gas main theregeneration of the catalyst in reaction zone Ia is complete. Thereaction zone is then purged with flue gas substantially devoid ofoxygen until about 5 to about l0 volumes of flue gas based upon thevolume of reaction zone Ia have passed therethrough. Valve 381 is thenopened and Valves 320 and 339 closed. Thereafter, valves 271 and 260 areopened putting reaction zone Ia back on stream. Thereafter, as thecondition of the catalyst in the other reaction zones requires, thecatalyst in reaction Zones Ib, Ic, IIa, IIb, IIC, Illa, IIIb and Illc isregenerated in any sequence in the manner described hereinbefore.

From the foregoing description of presently preferred methods ofreforming a mixture of hydrocarbons in the presence of hydrogen in aplurality of static beds of particle-form solid reforming catalyst,preferably platinumgroup metal reforming catalyst and particularlyplatinum reforming catalyst and presently preferred apparatus forpracticing the aforesaid novel method of reforming, those skilled in theart will understand that the present invention is a method of reforminghydrocarbon mixtures in the presence of hydrogen and reforming catalystin a plurality of reaction stages each having a plurality of reactionzones wherein the catalyst in at least one reaction zone but not morethan one reaction zone in any reaction stage is being regeneratedcontemporaneously with the reforming of hydrocarbon mixture in the otherreaction zones the catalyst in which is not being regenerated and anovel apparatus for practicing the aforesaid invention. Those skilled inthe art will also recognize that the present invention comprisesestablishing in each reaction stage a plurality of at least threereaction zones, charging each of said reaction zones with particle-formsolid reforming catalyst, the total amount of said charged catalystbeing greater than the amount of said catalyst required to provide theforesaid stage space velocity and the total amount of said catalyst inless than all of said reaction zones in a reaction stage being sulhcientto provide the aforesaid stage space velocity, in all reaction stagespassing said charge mixture in parallel through a plurality of selectedon-stream reaction zones to provide said stage velocity, excluding saidcharge mixture from the remainder of the reaction zones in a reactionstage, designated off-stream reaction zones, withdrawing reactionproducts from each of said selected on-stream reaction zones in areaction stage as a reaction stage eliuent, producing in said selectedon-stream reaction. zones a carbonaceous deposit on said catalystconfined therein, in a cyclic manner selectively discontinuing the flowof charge mixture to at least one of said selected on-stream reactionzones, designated hybrid reaction zone, in at least one reaction stage,introducing charge mixture selectively into the number of purgedoif-stream reaction zones in addition to selected on-stream reactionzones remaining onstream in each reaction stage to maintain theaforesaid stage space velocity, and contemporaneously sequentiallypurging said hybrid reaction zone, passing regenerating medium throughsaid purged hybrid reaction zone, and purging said hybrid reaction zoneto provide purged olfstream reaction zone.

I claim:

l. In the method of reforming naphtha wherein a charge mixturecomprising naphtha and hydrogen is contacted successively in a pluralityof adiabatic reaction stages with particle-form solid reforming catalystat reforming conditions of temperature, pressure, and liquid hourlyspace velocity, wherein the overall liquid hourly space velocity for allstages is in the range of about 0.2 to about 10 and the stage spacevelocity in each stage is greater than the existing overall liquidhourly space velocity wherein the effluent of each reaction stage isreheated to reforming temperature prior to introduction into asucceeding reaction stage, wherein the effluent of the final reactionstage is separated into reformer gas comprising hydrogen and C1 to C3hydrocarbons and reformate comprising C4 and heavier hydrocarbons,wherein at least a portion of asid reformer gas is recycled to saidreaction stages, wherein in an on-stream period carbonaceous material isdeposited on said catalyst, wherein the amount of said depositedcarbonaceous material in at least one reaction stage reduces theactivity of said catalyst therein to an impractical level, completes theon-stream period and initiates an off-stream period, wherein chargemixture is excluded from said reaction stage during said offstreamperiod, and wherein the activity of the catalyst in in said off-streamreaction stage is restored to a practical level by decomposition of saidcarbonaceous material in a regeneration medium during said off-streamperiod, the improvement which comprises establishing in each of theaforesaid reaction stages a plurality of at least three re- 9 actionzones, charging each of said reaction zones with particle-form solidreforming catalyst, the total amount of said charged catalyst beinggreater than the amount of said catalyst required to provide theaforesaid stage space velocity and the total amount of said catalyst inless than all of said reaction zones in a reaction stage beingsufficient to provide the aforesaid stage space velocit, in all reactionstages passing said charge mixture in parallel through a plurality ofselected on-stream reaction zones to provide said stage space velocity,excluding said charge mixture from the remainder of the reaction zonesin a reaction stage, designated off-stream reaction zones, withdrawingreaction products from each of said selected onstream reaction zones ina reaction stage as a reaction stage effluent, producing in saidselected ori-stream reac* Y tion zones a carbonaceous deposit on saidcatalyst confined therein, in a cyclic manner selectively discontinuingthe ow of charge mixture to at least one of said selected onstreamreaction zones, designated hybrid reaction zone, in at least onereaction stage, introducing charge mixture selectively into the numberof purged o-stream reaction zones in addition to selected on-streamreaction zones remaining on-strearn in each reaction stage to maintainthe aforesaid stage space velocity, and contemporaneously sequentiallypurging said hybrid reaction zone, passing regenerating medium throughsaid purged hybrid reaction zone, and purging said hybrid reaction zoneto provide purged off-stream reaction zone.

2. The method described and set forth in claim 1 wherein theparticle-form solid reforming catalyst is platinum-group metal reformingcatalyst, and wherein the reforming pressure is in the range of about toabout 300 p.s.i.g.

3. The method described and set forth in claim 1 wherein theparticle-form solid reforming catalyst is platinumgroup metal reformingcatalyst, wherein the reforming pressure is in the range of about 15 toabout 300 p.s.i.g. and wherein purge gas and regenerating medium iiowthrough said hybrid reaction zone at a pressure in the range of about 5to about 25 p.s.i. greater than the pressure in the selected on-streamreaction zones.

4. The method described and set forth in claim 1 wherein purge gas andregenerating medium ow through said hybrid reaction zone at a pressurein the range of about 5 to about 25 p.s.i. greater than the pressure inthe selected on-Stream reaction zones and wherein during the purge ofsaid hybrid reaction zone of hydrocarbon vapors about 2 to 6 volumes ofpurge gas flow from the aforesaid hybrid reaction zone with the effluentof said selected on-stream reaction zones.

5. The method described and set forth in claim 4 wherein the volume ofpurge gas passed through said hybrid reaction zone during each purge isat least twice the volume of said empty hybrid reaction zone.

6. In a horizontal cylindrical tank for catalytic hydroA carbonconversion at pressures up to 1000 p.s.i.g. in which hydrocarbonconversions the activity of the catalyst is reduced by depositionthereon of a carbonaceous material during an on-stream period and theactivity of said catalyst is restored to a practical level during anolf-stream period by decomposition of said carbonaceous material in astream of regenerating medium, said tank having (1) an end plate mountedvertically to the horizontal axis of said tank in a vapor-tight mannercontiguous to each end of said tank, (2) a plurality of spaced apartplates i mounted vertically to the aforesaid horizontal axis in avapor-tight manner between the aforesaid end plates and constructedandarranged to provide a plurality of vapor-tight major compartments,(3) a reactant inlet mounted in a vapor'tigl1t manner in a quadrantabove the aforesaid horizontal axis in each of said maior compara ments,and (4) a reaction products outlet mounted in a vapor-tight manner in aquadrant below the aforesaid horizontal axis in each of said majorcompartments, the

combination comprising in each of said major compartments a lirsthorizontal plate, having a plurality of inlet ports, mounted above saidhorizontal axis, in a vapor-tight manner parallel to said horizontalaxis, and constructed and arranged to form with the contiguous wall ofsaid tank a reactant inlet manifold; in each of said major compartmentsa second horizontal plate, having a plurality of outlet ports, mountedbelow said horizontal axis, in a vapor-tight manner, parallel to saidhorizontal axis, and constructed and arranged to form with thecontiguous wall of sai tank a reaction products outlet manifold; in eachof said major compartments a plurality of spaced apart plates mounted ina vapor-tight manner between said iirst and second horizontal plates,and constructed and arranged to form a plurality of vapor-tight minorcompartments therein each of which have iluid communication with thereactant inlet manifold of its major compartment through only one ofsaid inlet ports and lluid communication with the reaction productsoutlet mani@ fold of its major compartment through only one of saidoutlet ports; a thin walled inlet cylinder, deformable at operatingtemperatures of about 800 to about 1000 F. mounted in each of said inletports in a vapor-tight manner, a thin-walled outlet cylinder deformableat the aforesaid operating temperatures mounted in each of said outletports in a vapor-tight manner; a first minor compartment sealing meansmounted above and vertically spaced apart from each of said inletcylinders and concentric therewith; a second minor compartment sealingmeans mounted below and vertically spaced apart from and concentric witheach of said outlet cylinders; said iirst and said second minorcompartment sealing means comprising a regenerating conduit resistant tosubstantial longitudinal compression mounted in a port in said tank in asliding, substantially vapor-tight manner, a tapered plug mounted in avapor-tight manner on the inner end of said regenerating conduit andconcentric therewith, said plug having a maximum outside diametergreater than and a minimum outside diameter less than the insidediameter of a thinwalled cylinder and being resistant to substantialdeformation when forced into a thin-walled cylinder, and means externalof said tank constructed and arranged for thrusting said plug into athin-walled cylinder to form a substantially vapor-tight joint and forwithdrawing said plug from said thinwalled cylinder, said first andsecond minor compartment sealing means being constructed and arrangedfor flow of reactants into and reaction products out of selected minorcompartments in a major compartment and for flow of regenerating mediuminto and products of regeneration out of the balance of the minorcompartments in said major compartments without substantial mixing ofreactants and reaction products with regenerating medium and products ofregeneration.

7. In the horizontal cylindrical tank for catalytic hydrocarbonconversion at pressures up to 1000 p.s.i.g. as described and set forthin claim 6 in each minor compartment a foraminous plate mounted abovesaid second horizontal plate below said horizontal axis.

References Cited in the iile of this patent UNITED STATES PATENTSHengstebeck Qct. 13, 1959

1. IN THE METHOD OF REFORMING NAPHTHA WHEREIN A CHARGE MIXTURECOMPRISING NAPHTHA AND HYDROGEN IS CONTACTED SUCCESSIVELY IN A PLURALITYOF ADIABATIC REACTION STAGES WITH PARTICLE-FORM SOLID REFORMING CATALYSTAT REFORMING CONDITIONS OF TEMPERATURE, PRESSURE, AND LIQUID HOURLYSPACE VELOCITY, WHEREIN THE OVERALL LIQUID HOURLY SPACE VELOCITY FOR ALLSTAGES IS IN THE RANGE OF ABOUT 0.2 TO ABOUT 10 AND THE STAGE SPACEVELOCITY IN EACH STAGE IS GREATER THAN THE EXISTING OVERALL LIQUIDHOURLY SPACE VELOCITY WHEREIN THE EFFUENT OF EACH REACTION STAGE INREHEATED TO REFORMING TEMPERATURE PRIOR TO INTRODUCTION INTO ASUCCEEDING REACTION STAGE, WHEREIN THE EFFUENT OF THE FINAL REACTIONSTAGE IS SEPARATED INTO REFORMER GAS COMPRISING HYDROGEN AND C1 TO C2HYDROCARBONS AND REFORMATE COMPRISING C4 AND HEAVIER HYDROCARBONS,WHEREIN AT LEAST A PORTION OF ASID REFORMER GAS IS RECYCLED TO SAIDREACTION STAGES, WHEREIN IN AN ON-STREAM PERIOD CARBONACEOUS MATERIAL ISDEPOSITED ON SAID CATALYST, WHEREIN THE AMOUNT OF SAID DEPOSITEDCARBONACEOUS MATERIAL IN AT LEAST ONE REACTION STAGE REDUCES THEACTIVITY OF SAID CATALYST THEREIN TO AN IMPRACTICAL LEVEL, COMPLETES THEON-STREAM PERIOD AND INITIATES AN OFF-STREAM PERIOD, WHEREIN CHARGEMIXTURE IS EXCLUDED FROM SAID REACTION STAGE DURING SAID OFFSTREAMPERIOD, AND WHEREIN THE ACTIVITY OF THE CATALYST IN IN SAID OFF-STREAMREACTION STAGE IS RESTORED TO A PRACTICAL LEVEL BY DECOMPOSITION OF SAIDCARBONACEOUS MATERIAL IN A REGENERATION MEDIUM DURING SAID OFF-STREAMPERIOD, THE IMPROVEMENT WHICH COMPRISES ESTABLISHING IN EACH OF THEAFORESAID REACTION STAGES A PLURALITY OF AT LEAST THREE REACTION ZONES,CHARGING EACH OF SAID REACTION ZONES WITH PARTICLE-FORM SOLID REFORMINGCATALYST, THE TOTAL AMOUNT OF SAID CHARGED CATALYST BEING GREATER THANTHE AMOUNT OF SAID CATALYST REQUIRED TO PROVIDE THE AFORESAID STAGESPACE VELOCITY AND THE TOTAL AMOUNT OF SAID CATALYST IN LESS THAN TOPROVIDE THE AFORESAID STAGE SPACE VELOCITY, IN ALL REACTION STAGESPASSING SAID CHARGE MIXTURE IN PARALLEL THROUGH A PLURALITY OF SELECTEDON-STREAM REACTION ZONES TO PROVIDE SAID STAGE SPACE VELOCITY, EXCLUDINGSAID CHARGE MIXTURE FROM THE REMAINDER OF THE REACTION ZONES IN AREACTION STAGE, DESIGNATED OFF-STREAM REACTION ZONES, WITHDRAWINGREACTION PRODUCTS FROM EACH OF SAID SELECTED ONSTREAM REACTION ZONES INA REACTION STAGE AS A REACTION STAGE EFFUENT, PRODUCING IN SAID SELECTEDON-STREAM REACTION ZONES A CARBONACEOUS DEPOSIT ON SAID CATALYSTCONFINED THEREIN, IN A CYCLIC MANNER SELECTIVELY DISCONTINUING THE FLOWOF CHARGE MIXTURE TO AT LEAST ONE OF SAID SELECTED ONSTREAM REACTIONZONES, DESIGNATED HYBRID REACTION ZONE, IN AT LEAST ONE REACTION STAGE,INTRODUCING CHARGE MIXTURE SELECTIVELY INTO THE NUMBER OF PURGEDOFF-STREAM REACTION ZONES IN ADDITION TO SELECTED ON-STREAM REACTIONZONES REMAINING ON-STREAM IN EACH REACTION STAGE TO MAINTAIN THEAFORESAID STAGE SPACE VELOCITY, AND CONTEMPORANEOUSLY SEQUENTIALLYPURGING SAID HYBRID REACTION ZONE, PASSING REGENERATING MEDIUM THROUGHSAID PURGED HYBRID REACTION ZONE, AND PURGING SAID HYBRID REACTION ZONETO PROVIDE PURGED OFF-STREAM REACTION ZONE.